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. . FEE 05 ':'0 ;;-: 3.J ?: 3 Research Diecharaes Discharge variables that have been identified as driving variables are (1) the magnitude of fluctuation, (2) the minimum discharge, (3) the rate of change in fluctuating discharges both for increasing and decreasing releases, and (4) seasonal aspects of 1-3. These variables have been identified and are to be tested in hypotheses HO-1 to HO-7 in the Research Plan. In determining the discharges needed to produce adequate response curves, a dendroqrUl has been used (Fiqure 1). This figure shows a dichotomy between constant and fluctuating discharges. The fluctuating discharges are divided between discharges with low and high fluctuations (i.e., range between daily minima and maxima). Further divisions take into account the need to test various minimum discharges and ramping rates. The fluctuating diacharges (in dashed boxes) are put at the same level, in the diagram, in terms of daily volume as the comparable constant discharges. To test the influence of one driving variable on a particular Canyon resource, it is essential to keep other interactive variables constant. If this were carried to its ultimate extreme, the number of required research discharges would be unrealistically high. The number shown in Figure 1 then becomes a workable and realistic number of discharge regimes. In some cases it is impossible to keep all interactive variables constant. For example, if the variable to be studied is magnitude of discharge fluctuation, the minimum discharge could be kept constant (e.g, discharge A, D or E, and constant 3000, Figure 1): but, althouqh the daily volume could be the same for A, D or E, it would be considerably less tor the constant 3000. To use a constant discharge with volume equal to A, or 0 or E, a constant of 8,000 or 11,000 would have to be used. Ramping rates would also be variable. In a case where minimum discharge is the experimental variable, fluctuation and ramping can be kept constant (e.g., diSCharges A, 5, C: Figure 1) but the volume must obviouelY follow the increasing minimum discharges. As a result of limiting the number of research discharqes to tho.e shown in Figure 1, the response curve graphs for a particular experimental variable will have a series of curves tied to other interactive variables. This emphasizes the interactive nature of all of the driving variables as well as many of the response variables. Research discharge sequencing should tie together controlled fluctuating discharges with similar (by volume) constant discharges and be preceded or followed by normal operation discharges with similar volumes and patterns. Each research discharge sxperiment should also be followed by a low, constant 2